A shank slot dial is a cylindrical fixture commonly used in the fabrication of screws, bolts, or other elongate threaded components to render the components self tapping. The slot dial fixture rotates about its longitudinal center axis, and has uniformly spaced notches formed on its outer cylindrical surface that receive and hold the diameter or shank sections of the individual threaded components. The threaded components are snuggly held in the notches by surrounding guide means and by axially biased clamp means acting against the heads of the components. The fabricating machine has powered cutting or grinding means urged against the pointed tip or lead end of the threaded component to slot or groove the end tip.
Because of the large cutting forces, only a small portion of the pointed tip or lead end of the component can be unsupported or cantilevered beyond the supporting fixture. Otherwise, abnormal deflections of the component and possible damage to the component or to the cutting means can take place. Further, the dial notches have to be sized only slightly larger than the diameter or shank sections of the threaded components so that the threaded components can be solidly retained within the notches during the fabrication. For these reasons, it is typical to provide a specific shank slot dial for each size threaded component, including different shank or diameter sizes, and also for different component lengths. The type or pitch of thread on the threaded component generally does not alter the requirements of the shank slot dial.
Because of the large number of conventional screw sizes varying both in diameter and length, considerable capital investment is required for inventorying a separate properly sized dial for each particular size of threaded components to be fabricated. This burdens set up time also in converting from one slot dial to another slot dial between runs of different length threaded components.